• Tribology and Lubricants
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• v.16 no.5
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• pp.389-394
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• 2000

Scanning Probe Microscope (SPM) such as Scanning Tunneling Microscope (STM) and Atomic Force Microscope (AEM) was shown to be the powerful tool for nano-scale characterization of material surfaces. Using this technique, surface morphology of the cyclically deformed Cu or Cu-Al single crystal was observed. The surface became proportionately rough as the number of cycles increased, but after some number of cycles no further change was observed. Slip steps with the heights of 100 to 200 nm and the widths of 1000 to 2000 nm were prevailing at the stage. The slipped distance of one slip system at the surface was not uniform, and formation of the extrusions or intrusions was assumed to occur such place. By comparing the morphological change caused by crystallographic orientation, strain amplitude, number of cycles or stacking fault energy, some interesting results which help to clarify the basic mechanism of fatigue damage were obtained. Furthermore, applicability of the scanning tunneling microscopy to fatigue damage is discussed.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.149-149
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• 2003

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2009.10a
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• pp.606-608
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• 2009

• Proceedings of the Korean Society of Life Science Conference
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• 2008.10a
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• pp.42.2-42.2
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• 2008

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1993.11a
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• pp.18-19
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• 1993

• 대한치주과학회:학술대회논문집
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• 1994.12a
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• pp.54-54
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• 1994

• Journal of Nutrition and Health
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• v.21 no.3
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• pp.154-163
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• 1988

Effects of alchohol and fat content in a balanced diet on chemical composition and morphology of liver were investigated in growing rats. Fourth eight male rats of Sprague-Dawley strain weighing about 160g were divided into 4 groups ; high fat diet group, alcohol-administered high fat diet group, low fat diet group and alcohol-administered high fat diet group, low fat diet group and alcohol-administered low fat diet group. High and low fat diets supplied 30% and 12%, respectively, of total calorie intake from fat, and alcohol was given by adding ethanol in drinking waster at 10%. Diets contained adequate amounts of all nutrients required for rats, including lipotrpoic agents(choline and methionine) to minimize effects of factors other than alcohol on liver damage. Ratios of liver weight to body weight were statistically different among groups. Liver/dody weight ratios alcohol-administered rats were significantly higher than those of non-alcohol groups after 6 weeks treatment. Although total lipid and triglyceride per gram liver were increased in alcohol-administered rats, especially low fat diet fed rats, the values were not significantly different. Opticmicroscopical observation revealed increase in cell size and no change in morphology of liver. Examination of hepatocytes by electron microscopy showed that fat droplets were observed in all groups but enlarged in the alcohol-administered low fat diet fed rat. Contents of protein, cholesterol and phospholipid were not affected by alcohol consumption. The level of lipid peroxide was significantly lower in the livers of alcohol-administered rats than in the livers of non-alcohol groups. The results of this study indicate that even moderate alcohol drinking and dietary fat content did not affect any significant change in composition and morphology of liver until 6 week treatment but that even moderate alcohol drinking caused some signs of steatosis of liver.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.611-622
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• 2016

Particle morphology change and different experimental condition analysis during composite fabrication process by traditional ball milling with discrete element method (DEM) simulation were investigated. A simulation of the three dimensional motion of balls in a traditional ball mill for research on the grinding mechanism was carried out by DEM simulation. We studied the motion of the balls, the ball behavior energy and velocity; the forces acting on the balls were calculated using traditional ball milling as simulated by DEM. The effect of the operational variables such as the rotational speed, ball material and size on the flow velocity, collision force and total impact energy were analyzed. The results showed that increased rotation speed with interaction impact energy between balls and balls, balls and pots and walls and balls. The rotation speed increases with an increase of the impact energy. Experiments were conducted to quantify the grinding performance under the same conditions. Furthermore, the results showed that ball motion affects the particle morphology, which changed from irregular type to plate type with increasing rotation speed. The evolution was also found to depend on the impact energy increase of the grinding media. These findings are useful to understand and optimize the particle motion and grinding behavior of traditional ball mills.

• Journal of the Speleological Society of Korea
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• no.68
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• pp.99-120
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• 2005

It is a wrong decision to use only topographic and geological maps for the study of pediment morphology in Korea. For the study of pediment morphology it is necessary to survey the earth structure by field techniques. In Korea, pediments are mostly found in granite areas with hardrock cover. But, pediments also developed in gneiss areas and what is worse in limestone areas. So, all areas in Korea developed pediment morphology. Only in South Korea pediments show a direction from south to north or from west to east. They developed only in right angles to each other, either parallel or in right angles to the strike, depending on the bedrock structure. Pediments are found in two levels. The upper level pediments are correlated with the lower level erosion surface. Besides this pediments are found in Hoenggye-ri of the Taegwolryong area in a third level 800m above sea level. The pediments developed in basins, at the lower margins of steep slopes dividing three levels of erosion surfaces and around the residual mountains on the erosion surfaces. The first belong to the early stage of pedimentation, the second to the middle stage and the third to the last stage. Also, in Korea monadnock and residual mountain have developed the pediments are correlated the slope of the hinter mountains. Akagki states that the only pedimentation times have been times of arid climate and that they are dissected by gulley erosion with climatic change, but writer's study proves that pedimentation takes place with eustatic movement, reckless defore-station and convectional rain. These facts indicate that the landforms, geological character and process of erosional cycle of the pediments in Korea resemble much those in the Chugoku Mountains of south wertern Japan, but they are larger in scale than those in the Chugoku Mountains. In conclusion, while Akagki emphasizes the geological character and climatic change in pedimentation, the writer studies prove that eustatic movements, especially the sea level rise after the Wurm age are important factors for pedimentation. Besides this the author's studies allow a classification of gentle slopes.

• Korean Chemical Engineering Research
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• v.56 no.2
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• pp.191-203
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• 2018

This study was investigated the effect of the morphology change of copper (Cu) powders under the different rotational speed and milling time by using three kinds of grinding media with different size and materials, and performed DEM simulations of ball behavior. In order to clarify the mechanism of grinding by three - dimensional simulations of the ball behavior in a traditional ball mill, the force, kinetic energy, and medium velocity of the grinding media were calculated. In the simulation, the amount of change of the input energy was also calculated by adjusting the rotational speed, ball material, kinetic velocity, and friction coefficient in the same as the actual experimental conditions. The scanning electron microscope results show that the particle morphology changes from irregular to spherical when the ball size is small.